Obesity is a growing problem not only in the United States, but worldwide as well, and for the first time, researchers are able to say just how big of a problem it actually is. (Photo: Reuters / Phil Noble)

Obesity is a growing problem not only in the United States, but worldwide as well, and for the first time, researchers are able to say just how big of a problem it actually is. Humans are more than 17 million tons overweight, according to a new study, published in the journal BMC Public Health on Monday.

The extra weight is the equivalent of having an extra 242 million people on the planet, researchers said, and could have implications for food sources in the future.

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"[United Nations] world population projections suggest that by 2050 there could be an additional 2.3 billion people," researchers wrote. "The ecological implications of rising population numbers will be exacerbated by increases in average body mass."

As people get fatter, they need more calories to sustain themselves. This means that looking at sheer numbers in terms of population growth is inaccurate, according to the study.

"Although the largest increase in population numbers is expected in Asia and sub-Saharan Africa, our results suggest that population increases in the USA will carry more weight than would be implied by numbers alone," researchers wrote.

The United States is the heaviest nation in the world, according to the United Nations. The average global body weight is 138 pounds, but for North America, the average weight is 178.

"When people think about environmental sustainability, they immediately focus on population," Professor Ian Roberts, study author and researcher at the London School of Hygiene and Tropical Medicine, told BBC News. "Actually, when it comes down to it, it's not how many mouths there are to feed, it is how much flesh there is on the planet."

Researchers said not only will food scarcity become a problem, health issues and medical costs will skyrocket as well.

An obese person's annual medical cost is $2,700 higher, in 2005 dollars, than a non-obese person, according to the study. In 2010 dollars, the last year data is available, that is equivalent to almost $3,000.

More than 35 percent of adults in the U.S. older than 20 are obese. In 1985, no state had an obesity rate higher than 14 percent. By 2010, no state had an obesity rate lower than 20 percent, according to the Centers for Disease Control and Prevention.

Costs associated with obesity accounts for $190 billion annually -- 121 percent higher than previous estimates. More than 20.6 percent of all national health expenditures is spent on managing obesity and the related plethora of health problems, according to a recent study.

"If every country in the world had the same level of fatness that we see in the USA," Roberts told BBC News, "in weight terms that would be like an extra billion people of world average body mass."